When it comes to air filters, thicker is better. A filter that is 4-5 inches thick has more surface area and allows more air to pass through than the common 1-inch oven filters. These thicker filters, known as media filters, are usually 4-5 inches thick compared to the 1-inch filters that can be found in grocery stores. There is no difference between 1 and 5 inch filters with the same Merv rating when it comes to the size of the particles they filter.
However, there is a difference in static pressure between the two. The 5 inch filter has more physical holes for air to pass through, making it easier for air to flow through. This means that larger filters will make the system less restrictive and put less strain on the fan motor, which will extend the life of the equipment. When shopping for an air filter, you may be tempted to get one with the highest MERV rating.
However, this isn't always the best option. If you get a filter with pleats that are too thick, it can get dirty quickly and make your air conditioning unit work harder than necessary. If you have a Lennox G60UH (X) natural gas forced air oven, it has a filter box that carries 5 filters, specifically type X6670. When shopping for an air filter, you will find a wide range of options available.
If you can't find Nordic Pure in your size or if you want to buy a new filter right away, Honeywell's FPR 9 filters and Filtrete's MPR 1500 filters are similar and widely available in retail stores. When it comes to replacing your air filter, it depends on the type of filter you have. If you use a 5 inch media filter, it should be replaced every 6 months up to one year. During a wildfire, you may need to change your filter more often than usual.
There are some indicators that can help you know when it's time to replace your filter such as a decrease in airflow or an increase in dust in your home. When looking at the most common filter levels for retail (MERV 1-16), Owen said this range “takes it from filters that could catch a golf ball - I'm exaggerating a bit - to filters that will catch almost everything”. He also noted that if you get a filter with pleats that are too thick, it can get dirty quickly and make your air conditioning unit work harder than necessary. You can also use air ionizers which can help treat the air around your home by eliminating allergens and viruses. If your HVAC system uses a coarser filter (usually 4-5 inches thick and mounted on the air handler), it's likely designed specifically for medium efficiency MERV filtration. Your oven processes the air around your home at a rate of seven times an hour in an average household. All of them (and Owen) told us that MERV filters in this range restrict airflow more than low-MERV filters, as measured by the drop in air pressure that filters create when installed. In short, 5 inch air filters are much better than 1 inch filters when it comes to keeping your home clean and healthy.
They are also more cost effective in the long run since they don't need to be replaced as often as thinner filters.